Giant Squid and Whale Sharks Aren't As Big As People Think

Below:

Next story in Science

When it comes to determining the size of giant squid and other
large sea animals, humans have a tendency to exaggerate, a new
study suggests.

A team of researchers compared scientific and popular media
reports of body sizes for 25 species of marine creatures,
including whales, sharks, squids, and other giant ocean dwellers,
and found that most of the animals were smaller than what was
reported.

"It's human nature to tell a 'fishing story,'" said Craig
McClain, a marine biologist at the National Evolutionary
Synthesis Center in Durham, North Carolina. In reality, "we're
horrible at saying what the size of something is, without
actually taking a measurement." [ Whale
Album: Giants of the Deep ]

Size matters

It's been widely reported that
giant squid (Architeuthis dux) can reach lengths of
about 60 feet (18 meters). But real measurements show that these
creatures are actually closer to 40 feet (12 m) long, and even
that is extremely rare, McClain told Live Science.

When one of McClain's students noticed the same thing about
reports of
whale sharks (Rhincodon typus), the researchers
decided to conduct a systematic study of reported sizes for large
marine animals. They pored through the scientific literature and
popular media accounts, examined museum collections and spoke
with expert colleagues to track down real size measurements for
the animals studied.

The researchers created a database for each colossal creature,
with the average and maximum reported measurements, because, as
McClain put it, "Asking how big a human is, on average, is a lot
different than asking about the tallest human."

For many of these marine megafauna, reported sizes were
overestimated, the researchers found. For example, the world's
largest gastropod, an Australian trumpet snail (Syrinx
aruanus), was reported to be about 35.8 inches (91
centimeters), but the correct measurement for that specimen is
actually about 28.3 inches (72 cm).

The maximum size of a whale shark has also been exaggerated. Some
reports put the animal's length at 65.6 feet (20 m), but its
actual size is more likely 61.7 feet (18.8 m), the researchers
said.

The largest reported great
white shark (Carcharodon carcharias) is generally
thought to be about 23 feet (7 m), although some controversial
specimens have been larger, the researchers said.

Curiously, sharks that killed humans were reported as much longer
than those involved in just a bite, McClain said. One explanation
could be that people are more likely to exaggerate the size of a
more deadly animal. Or, it could be that larger sharks are more
aggressive. "We're not able to flesh that out," McClain said.

Weighing a whale

On the other hand, the reported sizes of a few of the species
studied were fairly accurate. For instance, scientists know the
largest
blue whales (Balaenoptera musculus) reach lengths of
about 108 feet (33 m) because of data from the whaling industry.

The sizes of other giant ocean creatures — such as the Japanese
spider crab (Macrocheira kaempferi) or
lion's mane jellyfish (Cyanea capillata) are harder
to pin down because the reports are anecdotal, McClain
said. Some estimates put the lion's mane at about 120 feet
(36.6 m), which would make it larger than a blue whale.

How does one even measure the size of a giant squid or a blue
whale? "It's difficult," McClain admits. Some animals, like
squid, simply wash ashore. For whale sharks, researchers can put
laser-reflective dots at a fixed interval on the creature's side
and extrapolate the length. For blue whales, whalers would cook
the animals down for fat, and determine the weight from how many
pots they had to use, McClain said.